Apparatus for determining the superficial resistance of pasteboard or paper



NOV. 19, DE VERDEER APPARATUS FOR DETERMINING THE SUPERFI CIAL RESISTANCE OF PASTEBQARD OR PAPER Filed Dec. 25, 1938 INVENTOR HIELM'ER DEIVER'DIER 6v W,

AT'TYS.

Patented Nov. 19, 1940 UNITED STATES PATENT OFFICE OR PAPER I-Ielmer de Verdier, Fredriksberg, Sweden Application December 23, 1938, Serial No. 247,514 In Sweden April 30, 1936 1 Claim.

The present invention relates to an apparatus for determining the superficial resistance of pasteboard or paper, by subjecting a piece of pasteboard or paper clamped in a reciprocating holder to wearing in such a manner that said piece of pasteboard or paper under adjustable load is pressed against another piece of pasteboard or paper also clamped in a holder, which, however, is stationary.

The chief purpose of the invention is to obtain an apparatus for testing the superficial resistance of pasteboard intended for use in the manufacture of pasteboard cases for outer packing. The requirements which are made on the superficial resistance of such pasteboard, shall, on one hand, correspond to the stresses which occur when using the pasteboard for producing pasteboard cases and, on the other hand, also correspond to the wearing when using the pasteboard cases, particularly with regard to the Wearing of the same against floors and bottoms of wagons during transport.

At the preparatory treatment of pasteboard intended for cases a great number of sheets, especially cut to size and glued together, are piled up, whereby a certain pressure according to the unit of surface arises on the lowest pasteboard sheet. In the machines, which work these sheets there is usually a special arm which suddenly feeds forward the lowest of these sheets. Due to this a certain load on the surface of the pasteboard occurs. After having been subjected to static compression, the pasteboard receives a sudden, violent, accelerated motion in a certain determined direction, whereby certain stresses arise between the pasteboard surfaces resting against each other. These stresses are capable of causing socalled cleavage of the surface of the pasteboard.

The invention relates to an apparatus, which is made With a reciprocating lineal motion, in which the working surfaces facing each other consist of two convex, cylindrical surfaces, which under adjusted load are pressed against each other, whereby a corresponding effect is obtained. For at the turning point the desired stage of rest is obtained, which then immediately changes into a violent accelerated motion. Due to the fact that the surfaces facin each other are convex there arises at the very turning point an additional pressure load between the surfaces, said pressure also being intended to imitate reality. During the rest of the motion the testing corresponds to that wearing which is caused when a pasteboard case with its contents is dragged over a floor.

The apparatus according to the invention is now characterized in that one holder has a twofold motion relatively to the other, namely on one hand a rectilinear reciprocating working motion along the same and, on the other hand, a pressing motion about perpendicular to the former motion. One or both of the holders has or have, respectively, a clamping device, consisting of a screw extending through the holder in the direction of motion and of movable end pieces on the ends of the screw, both ends of a pasteboard or paper strip being squeezed against the holder by means of certain clamping members and the movable end pieces. The lower holder is secured to a base or frame, the other being movable on the former in a reciprocating manner and capable of being loaded by means of weights, spring pressure or the like and hingedly united with a driving mechanism, so that it may be lifted. off from the lower holder for inspecting the progression of the testing.

The invention is illustrated in one embodiment on the accompanying drawing. Figures 1, 2 and 3 show the apparatus in side view, in plan view and from one end, in the two first-mentioned figures partly in section.

The reference numerals l and 9 indicate two holders, each for a pasteboard strip, in this embodiment made in the shape of plates with clamping devices for the pasteboard strips applied to them. The plates are so made that the surfaces facing each other are convex. It is suitable to form the convex surfaces as parts of a cylinder, the generatrix of which is perpendicular to the path of motion of the reciprocating plate. The lower plate is fixed to a frame plate la by means of bolts 9a.

By means of a clamping device a pasteboard strip of the quality to be tested may be fastened in such a manner that it lies stretched on the lower side of the plate I. This clamping device may be made with a tightening screw 2 extending all the way through and two end pieces 3 and 4, capable of being displaced on the studbolts 5, which are threaded into said end pieces as at 6, whereby it is possible to hold the end pieces firmly against the plates l and 9 by means of stresses in the coil springs I. The clamping members 8 are mounted on the cross pieces H), which as nuts run on the screw 2. When fastening a pasteboard strip the ends of the same are inserted under the clamping members 8. the screw 2 being then tightened. Due to the motion of the cross pieces I!) caused thereby the clamping members 8 are squeezed against the pasteboard strip.

When continuously tightening the screw 2 the end pieces 3 and 4 are caused to move away from the plate, whereby an additional stretching of the fastened pasteboard strip is obtained. The plate 9 has a similar fastening device. The plate I is secured to the bolts l2 by means of nuts ll, said bolts being at the other end mounted on the cross piece 13. Due to this the plate I can be raised against the yoke I4 to enable the application of the pasteboard strips on the plates l and 9. The cross piece l3, which at reciprocating motion is guided by means of slide bars or guiding pins I5, is further connected to the crank H by means of the connecting rod 16, said crank being united with the shaft 18 which may be brought into rotation. A speed indicator I9 is also connected to the shaft l8 by means of belt driving l8a.

By bringing the shaft I 8 into rotation the plate I is put in a reciprocating motion on the plate 9. Due to the weight of this reciprocating plate itself and to additional loads, if any, by means of weights, spring pressure or the like, there are obtained, after certain numbers of revolutions, various stages of wearing of the surfaces of the two pasteboard strips, which work against each other. Usually the following well marked stages of wearing occur:

A. Beginning dust-forming.

B. Beginning forming of small rolls of fibres.

C. Beginning forming of big rolls of fibres.

D. Cleavage of the surface, when a peeling ocours.

The superficial resistance may, therefore, be indicated by means of, for example, the four letters ABCD, or by means of the letters ABC or by means of some other combination of the observed degree of wearing, or also by determining the reduction of weight of the pasteboard strips after a certain number of revolutions, the worn on fibres having been first removed.

One pasteboard strip may possibly be replaced by another material, for example by fine-grained sand paper, in which case, of course, the time of testing must be determined with regard to the wearing strength of this material. Perhaps it will be possible to reduce the time of testing by selection of material.

The term pasteboard is intended to include liner board and kraft liners board."

Having now described my invention, what I claim as new and desire to secure by Letters Patent is:

Apparatus for determining the superficial resistance of pasteboard or paper, comprising a,

stationary support having a rigid convex surface for supporting material to be tested, a movable support having a rigid convex surface for supporting material to be treated, means for mounting the movable support over the stationary support and with its convex surface in engagement with the convex surface of the stationary support, a reciprocating member adjacent the supports and reciprocating in a substantially horizontal plane, and arms hinged to the reciproeating member about a horizontal axis and connected to the movable support for reciprocating the movable support transversely of the stationary support to cause the crest of the convex surface of the movable support to move from one side to the other of the crest of the convex surface of the stationary support, said hinge connection between the movable support and reciprocating member enabling the movable support to be lifted from the stationary support for inspection of the convex surfaces.

HELMER. DE VERDIER. 

